If your element does not have a fixed width or height then you can't use the other solutions without using javascript to calculate the values.
Here is an alternative.
#dialogInvoice {
width: 390px;
height: 722px;
padding-top: 28px;
border-radius: 4px;
background: #ffffff;
position: absolute;
left:50%;
top:50%;
-webkit-transform: translate(-50%, -50%);
-moz-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);
}